Keyboard



FIG. 1 is a front perspective view of a keyboard showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a front view thereof;

FIG. 4 is a rear view thereof; and,

FIG. 5 is a left side view thereof.

Broken lines shown in the drawings illustrate portions of the keyboard, and form no part of the claimed design. 

The ornamental design for a keyboard, as shown and described. 